textproduct: Rapid City

KEY MESSAGES

- Rain and snow chances increase Sunday into Monday, with the heaviest precipitation favored across the Black Hills and central South Dakota.

- Cooler, unsettled weather continues through next week, with a gradual warming trend towards the end of the week.

UPDATE

Issued at 957 PM MDT Sat Apr 25 2026

Large stacked low is continuing to drift across central Canada, with southwest flow aloft across the central CONUS. Very active SW flow stretches from the Great Basin to the northern Plains, which is expected to bring precipitation to the region over the next 48 hours. Surface obs show temps dropping into the 30s across the plains, while the Black Hills are in the 20s. Forecast for the upcoming precipitation is still on track. Models are in good agreement that the bulk of precip will be across East River SD, extending westward into the far eastern portions of the CWA. South Central SD could see over an inch of QPF...some models are even suggesting 2 inches. The driest part is expected to be across NW SD. Otherwise the rest of the CWA still looks to be solidly in the 0.25-0.75" range. The system may bring 1-3" of snow across the Black Hills and an inch or two across portions of NE WY Sunday night into Monday morning. A tightening pressure gradient behind a surface low will lead to gusty winds across the western/central SD Monday. A secondary wave may bring another round of light QPF to the area Monday night into Tuesday...with an inch or so of snow across the Black Hills Monday night.

DISCUSSION

(This Evening Through Saturday) Issued at 123 PM MDT Sat Apr 25 2026

Current upper-air water vapor imagery depicts the upper low over southern SK, with multiple shortwaves embedded within the southern half of the flow. At 500mb, a jet streak of 60kts is located over the CWA, supporting lingering rain/snow showers over portions of the CWA (per regional radar loop). Webcams are currently showing light snow showers over portions of the Black Hills. WV imagery indicates increasing low-level cloud cover across much of the CWA. Current surface observations show temperatures in the mid 30s to mid 40s on the plains and 20s in the Black Hills. Winds are westerly/northwesterly over northwestern SD, gusting to 30 mph, while the rest of the region is under lighter variable winds.

Current ensemble guidance suggests that the next system expected to move through on Sunday has slowed down, resulting in the upper low now slowly lifting northeastward Sunday morning (compared to late Saturday night/early Sunday morning on previous runs). This shift is likely to result in the main onset of rain/snow not occurring until later Sunday morning. With this shift in timing, precipitation is expected to persist through Monday afternoon. The highest QPF amounts have shifted farther eastward (over eastern SD), however, the 48 hr prob for >0.5" through 12Z Tuesday continues to show a 65 to 85% chance (NBM-CONUS) for much of western SD. Northeast WY is looking less likely to see those amounts with only a 20 to 35% chance (NBM-CONUS). Snowfall is expected to remain mainly confined to the Black Hills, where there is a 45 to 65% chance (NBM-CONUS) for >3" of total snowfall during the period.

As the upper low moves out, drier but still unsettled conditions are expected through the rest of the week. A few weak disturbances may bring additional beneficial precipitation to the region. Temperatures are expected to remain at or below average for the week, with highs mainly in the 50s and 60s after Monday.

AVIATION

(For the 06Z TAFS Through 06Z Sunday Night) Issued At 1041 PM MDT Sat Apr 25 2026

VFR conditions are expected to hold across the forecast area tonight, with mid-level clouds starting to thicken and lower by mid-morning Sunday as SE winds become modestly more gusty. This will be in advance of an approaching, strengthening shortwave trough that will spread our next round of organized rain/snow into the region Sunday afternoon. Guidance has trended a bit later with initial, somewhat showery stages of this activity...and have thus pushed the -SHRA TEMPO off until 17z/11am at KRAP and have maintained a 21z/3pm start time to long-duration showers and precip at KGCC. KRAP may need to be upgraded from it's current TEMPO as well to something longer/more predominant, depending on how models trend overnight/Sunday morning. Once any precip begins, cigs are expected to lower to at least low-end MVFR, with some guidance quickly reaching IFR and lowering vsbys significantly as well. For now this seems a touch aggressive, with the greatest low-level moisture and steadiest precipitation more likely toward the end of the current TAF period Sunday night, so have held cigs/vsbys just above most of the guidance for now and we can trend/massage as needed into "the main event". Some BR/FG is possible with the precip Sunday night as well, potentially lowering vsbys even when/where precip type remains rain. Bottom line...it's looking MOIST.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.